Deep fiber push connector that allows for rotation during tightening without damaging cable

ABSTRACT

A connector includes a first connector body and a second connector body configured to be coupled to one another. The first connector body has a through hole and a cavity. The through hole and the cavity are configured to receive a shield of a hardline coaxial cable. A first washer is disposed in the first connector body and is configured to permit the shield to be pushed in a first direction through the through hole and into the cavity while resisting movement of the shield in a second direction opposite to the first direction. The second connector body has a through hole and a cavity. The through hole and the cavity of the second connector body are configured to receive a tubular member. A second washer is disposed in the second connector body and is configured to permit the tubular member to be pushed in the second direction through the through hole of the second connector body and into the cavity of the second connector body while resisting movement of the tubular member in the first direction. The second connector body is rotatable relative to the second washer and the tubular member until the second connector body and the first connector body are coupled together to a predetermined degree of tightness.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.16/581,631, filed Sep. 24, 2019, pending, which is a Continuation ofU.S. application Ser. No. 15/387,641, filed Dec. 21, 2016, now U.S. Pat.No. 10,422,955, which claims the benefit of U.S. Provisional ApplicationNo. 62/387,052, filed Dec. 21, 2015, the disclosures of which areincorporated herein by reference

Also, this application is related to U.S. application Ser. No.15/296,026, filed Oct. 17, 2016 and U.S. Provisional Application No.62/242,987, filed Oct. 16, 2015, the disclosures of which areincorporated herein by reference.

BACKGROUND

Consumer requests for Video on Demand, high definition content, andDOCSIS® 3.0 data services is consuming ever-increasing amounts ofnetwork capacity. Also, the pursuit of “green” business practices hasbecome desirable. Cable operators are able to increase network bandwidthsignificantly, while simultaneously lowering energy consumption andimproving operational efficiency, by driving fiber deeper into thenetwork and reducing the number of homes served per node, for example,from 500 to 2,000 homes in a traditional hybrid fiber coax (HFC)architecture to typically around 100 homes.

By pushing fiber deeper into the network, typically within a few hundredfeet of the subscribers' homes, the optical-to-electrical conversion ofdownstream signals occurs much closer to subscribers' homes, whicheliminates the need for RF amplifiers in the coax plant, therebyachieving significant green benefits. With the length of the coaxialcable runs shortened, that portion of the network becomes entirelypassive. As this reduces the size of node service areas, it in turnresults in an increase of the narrowcast bandwidth available toindividual subscribers.

Conventional construction methods for installing fiber optic micro cabledeeper into the network require digging, trenching, boring, andrestoration. Such methods impact customer landscaping, lawns, and otherutilities including water, power, and gas lines.

More recently, alternative fiber deployment techniques have beendeveloped whereby cable operator coaxial cables are converted tofiber-optic cables, which allows the operator to deploy fiber deeper inthe network. These techniques remove the dielectric and center conductorof a hardline coax cable, while leaving the aluminum shield of thehardline coax in place for use as a conduit or micro-duct for installingfiber optic micro cable. These alternative deployment techniques are atsubstantially lower cost than traditional boring and trenching and takea fraction of the time. By avoiding digging, trenching, boring, andrestoration, impacts to customer landscaping, lawns, and other utilitiesincluding water, power, and gas lines are avoided.

These alternative techniques typically involve attaching a hydraulicfitting to an end of an existing coax cable and injecting abiodegradable soap solution into the coax under pressure. This fluidcompresses the foam core, breaking it from the shield, and pushes it outthe far end. The remaining aluminum shield of the hardline coax iscleaned and then used as a conduit or micro-duct for installing fiberoptic micro cable. These techniques are referred to as high pressurecoax core ejection and fiber optic cable injection (“coax ejection andfiber injection techniques”).

In order to create longer continuous lengths of hollowed-out hardlinecoax cables, separate spans of coax cables that terminate at a splicepoint can be connected by airtight fittings. The coax ejection and fiberinjection techniques conventionally require a special connector to beattached to the end of the coax cable to accommodate the hydraulicfitting used in the core ejection process and another special connectorto facilitate injection of the fiber optic cable. Still anotherconnector is required for connecting the hollowed-out hardline coaxcable with a second hollowed-out hardline coax cable.

It may be desirable to provide a connector for use in coax ejection andfiber injection techniques that can accommodate the hydraulic fitting,facilitate injection of the fiber optic cable, and connect twohollowed-out aluminum shields of coaxial cables

In some aspects, it may be necessary to splice together two same cables,for example, two aluminum hardline cables. In such case, it may beimportant to have one side of the connector spin while both cables areassembled with both ends of the connector, for example, to avoid damageto one of the hardline cables that may be caused by frictional contactduring spinning of the connector while making the splice.

Thus, it may be desirable to provide a connector for use in a spliceconnection that permits one connector body to spin relative to a cableinserted therein while coupling the connector body to another connectorbody.

SUMMARY

According to various aspects of the disclosure, a connector includes afirst connector body and a second connector body configured to becoupled to one another. The first connector body has a through hole anda cavity. The through hole and the cavity are configured to receive analuminum shield of a hardline coaxial cable. A first washer is disposedin the first connector body and is configured to permit the aluminumshield to be pushed in a first direction through the through hole andinto the cavity while resisting movement of the aluminum shield in asecond direction opposite to the first direction. The second connectorbody has a through hole and a cavity. The through hole and the cavity ofthe second connector body are configured to receive a tubular member. Asecond washer is disposed in the second connector body and is configuredto permit the tubular member to be pushed in the second directionthrough the through hole of the second connector body and into thecavity of the second connector body while resisting movement of thetubular member in the first direction. The second connector body isrotatable relative to the second washer and the tubular member until thesecond connector body and the first connector body are coupled togetherto a predetermined degree of tightness.

In accordance with some aspects of the disclosure, a method of couplinga tubular member to an aluminum shield of a hardline coaxial cableincludes installing a first connector body on the aluminum shield,pushing the aluminum shield through a first washer disposed in the firstconnector body, pushing a tubular member through a through hole, acavity, and a second washer disposed in a second connector body, andcoupling a second connector body to the first connector body. The firstconnector body has a through hole and a cavity, and the through hole andthe cavity are configured to receive the aluminum shield. The firstwasher is configured to permit the aluminum shield to be pushed in afirst direction through the through hole and into the cavity whileresisting movement of the aluminum shield in a second direction oppositeto the first direction. The second washer is configured to permit thetubular member to be pushed in the second direction through the throughhole of the second connector body and into the cavity of the secondconnector body while resisting movement of the tubular member in thefirst direction. The second connector body is rotatable relative to thesecond washer and the tubular member during the coupling step until thesecond connector body and the first connector body are coupled togetherto a predetermined degree of tightness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary connector in accordancewith various aspects of the disclosure.

FIG. 2 is a cross-sectional view of the exemplary connector of FIG. 1 inan uninstalled state.

FIG. 3 is a magnified view of a portion of the cross-sectional view ofFIG. 2.

FIG. 4 is an exploded view of the exemplary connector of FIG. 1.

FIG. 5 is an alternative cross-sectional view of the exemplary connectorof FIG. 1 in an uninstalled state.

FIG. 6 is a perspective view of the exemplary connector of FIG. 1 in anassembled and partially-installed state.

FIG. 7 is a perspective view of the exemplary connector of FIG. 1 in aninstalled state.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIGS. 1-7 illustrate an exemplary connector 100 in accordance withvarious aspects of the disclosure. The connector 100 includes a firstconnector portion 110 and a second connector portion 150 that arecouplable to one another.

As shown in FIGS. 1-7, the first connector portion 110 includes a firstconnector body 112, a first seal 114, a first ring member 116, a firstwasher 118, and a second ring member 120. The first connector body 112includes a first end wall 122 having a through hole 124 sized andconfigured to receive an aluminum shield 190 (FIGS. 6 and 7) of ahardline coax cable. A second end 126 of the first connector body 112,opposite to the first end wall 122, includes a female threaded portion128. The first connector body 112 includes a cavity 130 between thefirst end wall 122 and the female threaded portion 128.

The cavity 130 is configured to receive the first seal 114, the firstring member 116, the first washer 118, and the second ring member 120.An inner peripheral wall 115 of the first connector body 112 defines afirst shoulder 132 spaced from the first end wall 122 and facing in adirection toward the female threaded portion 128. The first shoulder 132seats the first seal 114 and the first ring member 116. As best shown inFIG. 2, the first ring member 116 sandwiches the first seal 114 againstthe first shoulder 132. The first washer 118 is sandwiched between thefirst and second ring members 116, 120 along a longitudinal dimension ofthe first connector body 112.

According to various aspects, the first connector body 112 may beconstructed from aluminum and have a chromate conversion coatings suchas, for example, yellow iridite. The first and second ring members 116,120 may be constructed from brass and may be nickel-plated. The firstand second ring members 116, 120 can thus be press-fit into the cavity130 of the first connector body 112 such that the first and second ringmembers 116, 120 are held by an interference fit relationship with theinner peripheral wall 115 of the first connector body 112. The first andsecond ring members 116, 120 are assembled with the connector body 112such that the first washer 118 is held firmly in place along thelongitudinal dimension to maintain electrical continuity through thefirst and second ring members 116, 120 and the first washer 118. Thefirst washer 118 is also substantially centered relative to the cavity130 and the through hole 124.

Referring to FIG. 2, the first connector body 112 includes a secondshoulder 134 at an end of the cavity 130 opposite to the first shoulder132. The second shoulder 134 is spaced from the female threaded portion128 in the longitudinal dimension of the first connector body 112. Thesecond ring member 120 may extend from the cavity 130 beyond the secondshoulder 134, but a gap 135 is maintained between the female threadedportion 128 and the second ring member 120, as will be discussed below.

Referring to FIG. 4, the first washer 118 may be a stainless steelstamping comprising an annular portion 136 with a plurality ofinward-facing fingers 138. The fingers 138 extend from the annularportion 136 at an angle away from the first end wall 122 and toward thesecond end 126 of the first connector body 112. The radially inward-mosttips 140 of the fingers 138 define an opening 142 sized and configuredto be slightly smaller than an outer diameter of the aluminum shield 190of a hardline coax cable. When the aluminum shield 190 is pushed throughthe opening 142 of the first washer 118, the fingers 138 can bend in thelongitudinal dimension toward the second end 126 of the first connectorbody 112 to accommodate the slightly larger aluminum shield 190. Oncethe first connector body 112 is assembled on the aluminum shield 190,the resiliency of the fingers 138 urges the fingers 138 radially inwardtoward the aluminum shield 190 to provide a gripping force against thealuminum shield 190. The gripping force of the fingers 138 together withthe angled orientation of the fingers 138 helps to prevent the firstconnector body 112 from being removed from the aluminum shield 190 andfrom being pushed further through the cavity 130.

The second connector portion 150 includes a second connector body 152, athird ring member 153, a second seal 154, a third seal 155, a fourthring member 156, a second washer 158, and a pusher 160. The secondconnector body 152 includes a first end wall 162 and an inner surface163. The third ring member 153 has an outer dimension sized such thatthe third ring member 153 can be press fit into the second connectorbody 152 adjacent the first end wall 162 such that the third ring member153 is held by an interference fit relationship with the inner surface163 of the second connector body 152. The third ring member 153 has athrough hole 164 sized and configured to receive a tubular member 192such as, for example, an aluminum shield of a hardline coax cable.Referring to FIG. 5, a second end 166 of the second connector body 152,opposite to the first end wall 162, includes a male threaded portion168. The third seal 155 surrounds the second connector body 152 betweenthe male threaded portion 168 and a shoulder 157 at an end of the head159 of the second connector body 152 that is opposite to the first endwall 162.

Referring now to FIG. 3, the second connector body 152 includes a cavity170 defined by an axially-facing end surface 253 of the third ringmember 153, a radially-inward facing surface 252 of the second connectorbody 152, and an axially-facing shoulder 254 of the second connectorbody 152. The axially-facing end surface 253 faces a direction away fromthe first end wall 162 and the axially-facing shoulder 254 faces thefirst end wall 162, such that the axially-facing end surface 253 and theaxially-facing shoulder 254 face one another. The cavity 170 isconfigured to receive the second seal 154, the fourth ring member 156,the second washer 158, and a head portion 161 of the pusher 160. Thehead portion 161 has a larger outside diameter than a body portion 165of the pusher 160 so that the head portion 161 is maintained in thecavity, while the body portion 165 extends through an interior of themale threaded portion 168 and extends beyond a second end wall 169 (FIG.5) of the second connector body 152, which is at the end opposite to thefirst end wall 162. The body portion 165 has an outer peripheral surfacespaced from an inner surface 268 of the male threaded portion to avoidan interference fit, such that second connector body 152 can be rotatedindependently of and relative to the body portion 165.

The second seal 154 is disposed between the axially-facing end surface253 of the third ring member 153 and a notch 172 cut out of the innerperipheral surface of the fourth ring member 156 at an end of the fourthring member 156 that faces the third ring member 153. As best shown inFIG. 3, the second washer 158 is disposed between the fourth ring member156 and the head portion 161 of the pusher 160.

When the second connector body 152 is in an unassembled, pre-installedstate (i.e., before the tubular member 192 is inserted into the secondconnector body 152) and an assembled, partially-installed state (i.e.,when the tubular member 192 is inserted into the second connector body152, but before the second connector body 152 is tightened to the firstconnector body 112 to a predetermined degree of tightness, for example,fully tightened), the fourth ring member 156, the second washer 158, andthe head portion 161 of the pusher 160 are disposed in the cavity 170 ina floating, non-fixed manner. That is, outer peripheral surfaces of thefourth ring member 156, the second washer 158, and the head portion 161are spaced from the radially-inward facing surface 252 of the secondconnector body 152 to avoid an interference fit, such that secondconnector body 152 can be rotated independently of and relative to thefourth ring member 156, the second washer 158, and the head portion 161.Also, the adjacent radial surfaces of (1) the third ring member 153 andfourth ring member 156, (2) the fourth ring member 156 and the secondwasher 158, (3) the second washer 158 and the head portion 161 of thepusher 160, and (4) the head portion 161 of the pusher 160 and theaxially-facing shoulder 254 of the second connector body 152 are spacedfrom one another to avoid a press fit in the axial direction, such thatsecond connector body 152 can be rotated independently of and relativeto the fourth ring member 156, the second washer 158, and the headportion 161 in the unassembled, pre-installed state and the assembled,partially-installed state. Additionally, the fourth ring member 156, thesecond washer 158, and the head portion 161 are rotatable independentlyof one another in the unassembled, pre-installed state and theassembled, partially-installed state.

According to various aspects, the second connector body 112 may beconstructed from aluminum and have a chromate conversion coating suchas, for example, yellow iridite. The third and fourth ring members 156,156 and the pusher 160 may be constructed from brass and may benickel-plated.

Referring to again to FIG. 4, the second washer 158 may be a stainlesssteel stamping comprising an annular portion 176 with a plurality ofinward-facing fingers 178. The fingers 178 extend from the annularportion 176 at an angle away from the first end wall 162 and toward thesecond end 166 of the second connector body 152. The radially inwardmosttips 180 of the fingers 138 define an opening 182 sized and configuredto be slightly smaller than an outer diameter of the tubular member 192.When the tubular member 192 is pushed through the opening 182 of thesecond washer 158, the fingers 178 can bend in the longitudinaldimension toward the second end 166 of the second connector body 152 toaccommodate the slightly tubular member 192. Once the first connectorbody 112 is assembled on the tubular member 192, the resiliency of thefingers 178 urges the fingers 178 radially inward toward the tubularmember 192 to provide a gripping force against the tubular member 192.The gripping force of the fingers 178 together with the angledorientation of the fingers 178 helps to prevent the first connector body112 from being removed from the tubular member 192, while permitting thetubular member 192 to be inserted into and/or through the secondconnector body 152.

In use, for example, at a splice location of two runs of hardlinecoaxial cable, the connector 100 may be utilized during a process forremoving the core (i.e., the center conductor and dielectric) frominside of one hardline coaxial cable to create an open conduit. Theconnector 100 is then also utilized to facilitate injection of fiberoptic cable into the conduit and to splice the one hollowed-out hardlinecoaxial cable to a second hollowed-out hardline coaxial cable.

For example, the first connector body 112 may be assembled on a one endof a first run of hardline coax cable by pushing the aluminum shield 190through the through hole 124. The second shoulder 134 and/or the secondring member 120 can serve as an installation guide that indicates howfar to push the connector onto the aluminum shield 190. A hydraulicfitting (not shown) may be coupled to the first connector body 112 tofacilitate the ejection of the center conductor and dielectric. Once thecenter conductor and dielectric are ejected from the hardline cable,only the aluminum shield 190 remains. The hydraulic fitting may then beremoved from the first connector body 112.

A second hollowed-out hardline conduit 192 may then be inserted into thesecond connector body 152, as shown in FIGS. 6 and 7. The outerdimension of the second conduit 192 is sized slightly smaller than aninner dimension of the third ring member 153 so as to avoid aninterference fit relationship. The second connector body 152 may then bethreadably connected with the first connector body 112. For example, thefirst and second connector portions 110, 150 may be coupled to oneanother via the female threaded portion 128 of the first connector body112 that receives the male threaded portion 168 of the second connectorbody 152. The first and second connector bodies 112, 152 may includehexagonal outer surfaces to facilitate tightening of the couplingbetween the first and second connector bodies 112, 152. As described indetail above, the second connector body 152 is free to spin (with thethird ring member 153) relative to the conduit 192, as well as relativeto the fourth ring member 154, the second washer 158, and the pusher160, as the second connector body 152 is tightened to the firstconnector body 152.

As the second connector body 152 is rotated to approach a predetermineddegree of tightness, for example, a fully tightened position, relativeto the first connector body 112, an end face 167 of the pusher 160engages an end face 127 of the second ring member 120 (FIG. 7).Continued rotation of the second connector body 152 relative to thefirst connector body 112 to the predetermined degree of tightness, forexample, a fully tightened position, urges the pusher 160 toward thethird ring member 153, which is fixed relative to the second connectorbody 152 by their interference fit relationship. Consequently, thepusher 160 sandwiches the fourth ring member 156, the second washer 158,and the second seal 154 against the third ring member 153 to provide anaxial press fit relationship among those elements along the longitudinaldimension, thereby ensuring a grounded connection between the first andsecond conduits 190, 192 by way of the connector 100.

Also, when the first and second connector portions 110, 150 are coupledto one another to a predetermined degree of tightness, for example, afully tightened position, the third seal 155 is sandwiched between thehead 159 of the second connector body 152 and a longitudinal flange 113(FIG. 5) of the first connector body 112 to provide a weatherproof sealbetween the first and second connector bodies 112, 152. Meanwhile, uponinstallation, the first seal 114 cooperates with an outer surface of thealuminum shield 190 to provide a weatherproof seal, and the second seal154 cooperates with an outer surface of the tubular member 192 toprovide a weatherproof seal.

Fiber optic cable can then be injected through the first run of cable,through the connector 100 at the splice location, and through the secondrun of cable. The first connector body 112 may include a ground screw194 used to connect a ground path to the connector 100 at the splicelocation.

As described above, a stamped retention washer may be assembled inside aconnector in a loose state in the manufacturing process. This washerbeing loose allows for the connector to be installed on the cable whileallowing the connector nut (outer body) to be rotated independently ofthe washer, thus preventing the sharp grabbing teeth of the washer fromcutting into the cable and creating a weak spot or worse, cuttingthrough the cable. During the connector tightening process in the fieldapplication, the components are moved into a compressed state whereelectrical continuity is restored through the entire connector.

Additional embodiments include any one of the embodiments describedabove, where one or more of its components, functionalities orstructures is interchanged with, replaced by or augmented by one or moreof the components, functionalities or structures of a differentembodiment described above.

It should be understood that various changes and modifications to theembodiments described herein will be apparent to those skilled in theart. Such changes and modifications can be made without departing fromthe spirit and scope of the present disclosure and without diminishingits intended advantages. It is therefore intended that such changes andmodifications be covered by the appended claims.

Although several embodiments of the disclosure have been disclosed inthe foregoing specification, it is understood by those skilled in theart that many modifications and other embodiments of the disclosure willcome to mind to which the disclosure pertains, having the benefit of theteaching presented in the foregoing description and associated drawings.It is thus understood that the disclosure is not limited to the specificembodiments disclosed herein above, and that many modifications andother embodiments are intended to be included within the scope of theappended claims. Moreover, although specific terms are employed herein,as well as in the claims which follow, they are used only in a genericand descriptive sense, and not for the purposes of limiting the presentdisclosure, nor the claims which follow.

What is claimed is:
 1. A connector, comprising: a first connector bodyconfigured to receive a shield of a hardline coaxial cable; a secondconnector body configured to be coupled to the first connector body andto receive a tubular member; and a washer disposed in the secondconnector body, the washer being configured to permit the tubular memberto be pushed in a first direction through the second connector body andinto the first connector body while resisting movement of the tubularmember in a second direction opposite to the first direction, whereinthe second connector body is rotatable relative to the second washer andthe tubular member until the second connector body and the firstconnector body are coupled together to a predetermined degree oftightness.
 2. A connector, comprising: a first connector configured toreceive a hardline coaxial cable; a second connector configured to becoupled to the first connector, the second connector being configured toreceive a tubular member; and a washer disposed in the second connectorportion, the washer being configured to permit the tubular member to bepushed in a first direction through the second connector and into thefirst connector while resisting movement of the tubular member in asecond direction opposite to the first direction, wherein the secondconnector is rotatable relative to the second washer and the tubularmember until the second connector and the first connector are coupledtogether to a predetermined degree of tightness.
 3. The connector ofclaim 2, wherein the second connector includes a cavity, and wherein thewasher is disposed in the cavity in a floating, non-fixed manner.
 4. Theconnector of claim 2, wherein the washer includes an annular portion anda plurality of fingers extending radially inward from the annularportion, and wherein the plurality of fingers are configured toengagingly receive the tubular member.
 5. The connector of claim 2,wherein the second connector includes a connector body, a ring memberconfigured to be fixedly coupled with the connector body, and a pushermember configured to be movable in the connector body.
 6. The connectorof claim 5, wherein the washer is disposed between the ring member andthe pusher member in an axial direction of the second connector.
 7. Theconnector of claim 6, wherein the pusher member is configured to extendout of the connector body in the axial direction and into the firstconnector.
 8. The connector of claim 7, wherein the pusher member isconfigured to engage a surface of the first connector as the secondconnector is rotated relative to the first connector to approach thepredetermined degree of tightness.
 9. The connector of claim 8, whereinthe pusher member is configured to be urged in the first directiontoward the ring member as the second connector is further rotatedrelative to the first connector to the predetermined degree oftightness.
 10. The connector of claim 9, wherein the pusher member isconfigured to sandwich the second washer with the ring member at thepredetermined degree of tightness.
 11. A connector, comprising: a firstportion configured to receive a first conduit; and a second portionconfigured to be coupled to the first portion, the second portion beingconfigured to receive a second conduit, wherein the second portion isconfigured to permit the second conduit to be pushed in a firstdirection through the second portion and into the first portion whileresisting movement of the second conduit in a second direction oppositeto the first direction, wherein the second portion is rotatable relativeto the second conduit until the second connector portion and the firstconnector portion are coupled together to a predetermined degree oftightness.
 12. The connector of claim 11, further comprising a washerconfigured to be disposed in the second portion in a floating, non-fixedmanner.
 13. The connector of claim 12, wherein the washer is configuredto permit the second conduit to be pushed in a first direction throughthe second portion and into the first portion while resisting movementof the second conduit in a second direction opposite to the firstdirection
 14. The connector of claim 13, wherein the washer includes anannular portion and a plurality of fingers extending radially inwardfrom the annular portion, and wherein the plurality of fingers areconfigured to engagingly receive the second conduit.
 15. The connectorof claim 12, wherein the second portion includes a body, a ring memberconfigured to be fixedly coupled with the body, and a pusher memberconfigured to be movable in the body.
 16. The connector of claim 15,wherein the washer is disposed between the ring member and the pushermember in an axial direction of the second portion.
 17. The connector ofclaim 16, wherein the pusher member is configured to extend out of thebody in the axial direction and into the first portion.
 18. Theconnector of claim 17, wherein the pusher member is configured to engagea surface of the first portion as the second portion is rotated relativeto the first portion to approach the predetermined degree of tightness.19. The connector of claim 18, wherein the pusher member is configuredto be urged in the first direction toward the ring member as the secondportion is further rotated relative to the first portion to thepredetermined degree of tightness.
 20. The connector of claim 19,wherein the pusher member is configured to sandwich the washer with thering member at the predetermined degree of tightness.